This research proposal will investigate the mechanisms by which bacteria acquire the enzymatic abilities to permit them to utilize novel and uncommon chemicals as growth substrates. Specifically studied will be the ability of organisms in the genus Klebsiella to develop efficient metabolic pathways to permit them to survive and multiply when presented with certain unnatural carbohydrates as sources of energy and carbon. Using the present knowledge that regulatory mutations permit Klebsiella to utilize the pentoses D-arabinose and xylitol as growth substrates, attempts will be made to develop an efficient, regulated catabolic pathway for the degradation of D-arabinose, with each metabolic and genetic change characterized. Chemostat studies employing D-arabinose or xylitol as substrates will be used to test experimentally the concepts of genetic drift, gene duplication and gene translocation.